To ensure safety and efficiency of transportation, the traffic must be organized, especially in cities and towns where there is large volume of traffic needs. The control of traffic at intersections, where two or more roads either meet or cross, is essential to the organization of traffic in populated areas. The control is usually achieved by a signal-controlled system to allocate the time to indicate which traffic is allowed to proceed using traffic signals, usually electric. The performance of such system is responsible for the safety and efficiency of traffic in cities and towns.
FIG. 1 shows a traditional traffic allocation system 100. As shown in FIG. 1, when two roads AB and XY intersect, traffic needs to be controlled along four directions: AB, BA, XY, and YX. For each traffic direction, there are both through traffic and turn traffic (including left turn, right turn, and U turn). Thus, for two four-lane roads, AB and XY, with two lanes at each direction crossing at an intersection, the traditional system 100 allocates through traffic and right turn traffic to the curb lane using a through and right turn traffic marking 102, and through traffic and left turn traffic to the inner lane using a through and left turn traffic marking 104.
In addition to the allocation of space in terms of lanes, FIG. 2 shows an allocation of passing permit in the AB and XY intersection. As shown in FIG. 2, the traditional system uses four phases to direct the traffic movement in the intersection. Each traffic signal is represented by a number of letters and numbers, from left to right. The first letter (A, B, X, Y) represents the road on which the traffic signal controls the traffic movement. The second number indicates a traffic pattern, with number one (“1”) indicating a through traffic, and number two (“2”) indicating various turn traffics. The third letter, which follows the number (e.g., 2), further indicates the direction of the turn traffic, with U meaning U turn, L meaning left turn, and R meaning right turn. For example, A1 controls the through traffic on Road A, and X2L controls the left turn traffic on Road X.
There are 4 phases of traffic passing permit as shown in FIG. 2. During the first phase, the lights controlling the various traffics from Road A (A1, A2U, A2L, A2R) are green and other lights are red. During the second phase, the lights controlling the various traffics from Road B (B1, B2U, B2L, B2R) are green and other lights are red. During the third phase, the lights controlling the various traffics from Road X (X1, X2U, X2L, X2R) are green and other lights are red. During the fourth phase, the lights controlling the various traffics from Road Y (Y1, Y2U, Y2L, Y2R) are green and other lights are red. FIGS. 3-6 illustrate traffic movements corresponding to the various phases. Although the U turn traffic is also included in FIG. 2, U turn traffic is in general not permitted in a two-lane setting and is thus omitted in FIGS. 3-6.
FIG. 3 illustrates the traffic movements in the first phase of the traditional system, including pedestrian traffic 108, vehicle through traffic 110, vehicle right turn traffic 112, and vehicle left turn traffic 114. A1, A2, B1, B2, X1, X2, Y1, and Y2 are the traffic lights in the system for corresponding lanes. All the vehicle traffics on Road A, including the through traffic 110, and turn traffic 112 and 114, are permitted to proceed, while no vehicle is permitted to pass through the intersection from other roads. The pedestrian traffics 108 on both Roads AB and XY are possible but limited to half of the pedestrian crossing line 106 and the pedestrians are forced to stop in the middle of the cross line to avoid conflict with passing vehicles. Traffic accident is likely to occur if pedestrian proceeds into the vehicle pathway 112 or 114. Thus, both the pedestrian and the driver in the turning vehicle would have to reduce their speed to observe other traffics to avoid accident. In some jurisdictions, vehicles on Road B, X and Y are allowed to turn right even under the red light, further increasing the risk of collision between vehicles and pedestrians.
FIG. 4 illustrates the traffic movements in the second phase of the traditional system, including pedestrian traffic 108, vehicle through traffic 110, vehicle right turn traffic 112, and vehicle left turn traffic 114. All the vehicle traffic on Road B, including the through traffic 110 and turn traffic 112 and 114, are permitted to proceed, while no vehicle is permitted to pass through the intersection from other roads. The pedestrian traffics 108 on both Roads AB and XY are possible but limited to half of the pedestrian crossing lines 106 and the pedestrians are forced to stop in the middle of the cross line to avoid conflict with passing vehicles. Traffic accident is likely to occur if pedestrian proceeds into the vehicle pathway 112 or 114. Thus, both the pedestrian and the driver in the turning vehicle would have to reduce their speed to observe other traffics to avoid accident. In some jurisdictions, vehicles on Road A, X and Y are allowed to turn right even under the red light, further increasing the risk of collision between vehicle and pedestrian.
FIG. 5 illustrates the traffic movements in the third phase of the traditional system, including pedestrian traffic 108, vehicle through traffic 110, vehicle right turn traffic 112, and vehicle left turn traffic 114. All the vehicle traffics on Road X, including the through traffic 110 and turn traffic 112 and 114, are permitted to proceed, while no vehicle is permitted to pass through the intersection from other roads. The pedestrian traffics 108 on both Roads AB and XY are possible but limited to half of the pedestrian crossing lines 106 and the pedestrians are forced to stop in the middle of the cross lines to avoid conflict with passing vehicles. Traffic accident is likely to occur if pedestrian proceeds into the vehicle pathway 112 or 114. Thus, both the pedestrian and the driver in the turning vehicle would have to reduce their speed to observe other traffics to avoid accident. In some jurisdictions, vehicles on Road A, B and Y are allowed to turn right even under the red light, further increasing the risk of collision between vehicle and pedestrian.
FIG. 6 illustrates the traffic movements in the fourth phase of the traditional system, including pedestrian traffic 108, vehicle through traffic 110, vehicle right turn traffic 112, and vehicle left turn traffic 114. All the vehicle traffics on Road Y, including the through traffic 110, and turn traffic 112 and 114, are permitted to proceed, while no vehicle is permitted to pass through the intersection from other roads. The pedestrian traffics 108 on both Roads AB and XY are possible but limited to half of the pedestrian crossing lines 106 and the pedestrians are forced to stop in the middle of the cross line to avoid conflict with passing vehicles. Traffic accident is likely to occur if pedestrian proceeds into the vehicle pathway 112 or 114. Thus, both the pedestrian and the driver in the turning vehicle would have to reduce their speed to observe other traffics to avoid accident. Therefore, there are conflicts in all of the four phases of traffic movements.
FIG. 7 illustrates another traditional traffic system 200. As shown in FIG. 7, Road AB is now an eight-lane road, with four lanes for each direction. The curb lane (the right lane) is used for right turn traffic with a right turn marking 116; the innermost lane is used for left turn and U turn with a left and U turn marking 120; and the two inner lanes between the curb lane and innermost lane are used for through traffic with a through traffic markings 118. That is, if there are three or more lanes (Road AB), left turn traffic may take the left lane, right turn traffic may take the right lane, and through traffic may take the middle lane(s). For a two-lane road, U turn traffic is generally not permitted.
The same problems of traffic movement conflicts as previously described similarly exist in the traditional system 200 as shown in FIG. 7. For example, when the traffic on Road A is permitted to proceed, the through traffic, left turn traffic, right turn traffic, and U turn traffic are permitted to proceed, while no vehicle is permitted to pass through the intersection from other roads. The pedestrian traffics on both Road AB are possible but limited to half of the pedestrian crossing lines 106 and the pedestrians are forced to stop in the middle of the cross lines to avoid conflict with passing vehicles. Similarly, traffics on Road B, X, and Y are having the same traffic conflicts.
Therefore, as described in the preceding paragraphs, the traditional traffic allocation system is both unsafe and inefficient. Because pedestrians cross the road while vehicle traffics, including turn traffics, proceed, it is likely that pedestrian and vehicle traffic could enter the same space at the same time to cause collision. Both pedestrian and vehicles in the intersection are required to reduce their speed to observe other traffics to avoid accident. Lower speed in passing the intersection reduces the efficiency of the whole traffic system. In addition, U turn in the system is sometimes not allowed because it would significantly increase the risk of traffic accident.
The disclosed systems and methods are directed at solving one or more problems set forth above and other problems.